The present invention relates to the field of latches for doors and the like and more particularly to quick release latches for escape doors or hatches such as are used in buses and mobile homes.
In the prior art, Green, U.S. Pat. No. 4,303,572, discloses a latch for an escape door having a mechanism that can be operated to open the door quickly. Green's combination, however, does not provide means for holding the door in a partially open position.
The primary object of the present invention is to provide a latch that can be used not only to secure an escape door or hatch for vehicles such as buses and mobile homes but also to hold such a hatch door partially open so that it can serve as a vent.
The latch comprises two sets of generally opposing rods and cylinders, each having a cylinder that is closed on one end and open on the other and a rod that is slideably engageable with the open end of the cylinder. A first compression spring, fixedly attached to the closed end of the cylinder, is compressed by the rod when it is slideably engaged with the cylinder. The end of the rod distal the cylinder is pivotally connected to a frame for the hatch door. The exterior wall of each cylinder is rigidly secured to one of a pair of brackets. Each bracket has a hole for receiving a pin connected to one of a pair of support pedestals attached to the inside of the hatch door.
When the escape hatch is located in the ceiling of a vehicle, each cylinder is mounted with its closed end directed downwardly when the hatch door is closed. With the cylinder so mounted, the first compression spring simultaneously puts an upward pressure on the rod and supplies a downward force to the support pedestal to hold the hatch door closed. A rubber seal is provided to make the door rain-tight.
The hatch door can also be disposed so as to assume either a vent (partially open) or fully open position. To move the hatch door to the partially open position, a user simply applies a force to the inside of the hatch door. As the hatch door is pushed outwardly, the support pedestal is lifted upwardly, causing the bracket which is pivotally connected thereto to rotate. Simultaneously, the cylinder rotates until the closed end of the clinder abuts against a limiting stop mounted on a support block hingedly connected to the hatch door.
In the vent position, the stop, the cylinder contiguous thereto, and the rod are situated with their longitudinal axes disposed approximately parallel to each other and downwardly at a small angle to the horizontal. The first compression spring then exerts a side force with both lateral and upward components on the stop. To protect the hinge of the hatch door from an unbalanced side force, the limiting stops are disposed with respect to each other in such a way that the lateral components of the forces exerted by the first compression springs in the two cylinders cancel out. The latch according to the present invention is capable of holding the hatch door in a partly open position so that the door can serve as a vent even while the vehicle is moving.
The support block, upon which the stops for the cylinders are mounted, is maintained, except when the hatch door is fully open, in a configuration in which the block is spaced apart a substantial distance from the inside surface of the hatch door. The block is biased to maintain this configuration, when the hatch door is in either the closed or the vent (partially open) position, by a second compression spring. The second compression spring can be used to rotate the block about a pair of hinges connecting it to the hatch door. A foot that projects perpendicularly from the block abuts the hatch door in said configuration and limits the direction in which the block can be rotated.
Each of the stops is mounted on the block proximate the points of attachment of the foot to the block and rearwardly of its leading edge. When a portion of the block away from the stops and the foot is pressed toward the hatch door, the block rotates about the hinge. With the block so rotated, the closed ends of the cylinders miss the stops, allowing the hatch door to be pushed fully open. When the hatch door is opened sufficiently, each of the rods leaves the cylinder with which it has been slideably engaged but remains pivotally attached to the frame of the door. For closure, the hatch door must be pulled toward the frame and each rod reinserted into one of the cylinders.
For external rescue, the hatch is equipped with a release handle or knob that is attached to the block by a flexible chain. When the knob is pulled, the block rotates about the hinge in much the same manner as if the leading edge of the block had been pressed toward the hatch door from the inside of the vehicle, thereby allowing the hatch door to be pulled fully open.